Superelastic collisions [e+Mg*] following resonant, 2-photon ionization of Mg atoms

Photoelectron energy spectra of electrons extracted from Mg vapor illuminated with resonance radiation (Mg 1S→Mg 1P→Mg++e) show not only the expected 1.1 eV electrons from the (1+1) process. They also show two bands of faster electrons that have been produced by inelastic collisions of the second kind--up-conversion--of the 1.1 eV electrons with the excited 1P Mg atoms. One band, at 2.7 eV, appears to be due to transfer of energy to a free electron as a magnesium atom de-excites from the 1P to the 3P state. Faster electrons, at 5.5 eV, appear to be produced by a 3-photon ATI process, or by a superelastic collision process de-exciting the 1P magnesium atoms to their ground state or by both; which process or processes are involved is under investigation as this is written. Approximate cross sections will be reported